The Identity and Inverse Matrices Get out your notes and purple sheet and get ready for a warm-up!
Warm-Up Determine if there is an inverse for the following matrix. If there is, find the inverse. 6 7 1 2
Reminders… 1 0 0 1 1 0 0 0 1 0 0 0 1 𝑎 𝑏 𝑐 𝑑 −1 = 1 𝑎𝑑−𝑏𝑐 𝑑 −𝑏 −𝑐 𝑎 What is the identity for a 2x2? 3x3? 1 0 0 1 1 0 0 0 1 0 0 0 1 How do we know if a matrix has an inverse? Find the determinant. If the determinant doesn’t equal 0, then it exists. What is the formula for the inverse once we know it exists? 𝑎 𝑏 𝑐 𝑑 −1 = 1 𝑎𝑑−𝑏𝑐 𝑑 −𝑏 −𝑐 𝑎
Closure Find the inverse. 5 0 1 0